draft builds and dist-repo

[Steve Traylen]

I have been trying out draft builds in our koji instance. 
The draft build, promote and setting up the extra acls to confine drafts to a particular tag are all working well.

When running   "koji dist-repo" against a tag containing draft builds it fails very  deliberately[1]. I was thinking to add
some other options  --skip-draft, --with-draft options to  "dist-repo" somewhat like  is already present with "list-tagged" and "--draft" , "--no-draft". Motivation here is we have
always generated yumrepos of our build destination tags using dist-repo and that with the addition of a draft build this is currently not possible.

* "--skip-draft" would grab just latest non-draft builds.   (The one we would actually use)
* "--with-draft" would grab latest builds which may be a draft.  ( Probably would not use )

default behaviour could stay the same.

[1] https://pagure.io/koji/c/3b1df037be675dfd58e2385065e0f5cd576696a1